Piston Slap: The Truth About "Throwaway" Motors (Part II)

Bob M. writes:

Sajeev, I’m a bottom feeder with cars. All I’ve ever owned are used domestic cars with pushrod engines. I overhauled a Pontiac 2.5L once just to get the experience. My idea of engine maintenance is valves at 100k and an overhaul at 150k.

I’ve heard that many imports aren’t rebuildable because the cylinder walls of the block are too thin. Can you enlighten me about what people do these days when their engines are wearing? Are valve jobs common? Are some brands more repairable than others? What lifespans do people expect to get from modern engines?

Keep on Truckin’

Sajeev answers:

My how times have changed! While plenty of older cars (even the Iron Duke GM engines) don’t absolutely demand your 100k/150k regiment, you are committed to the best performance from these ancient, antiquated designs. Sadly, your thinking is far out of line with modern engine design.

Fancy, modern aluminum castings have completely changed the game…for the better. Expensive to replace torque-to-yield bolts? Not so much. Fact is, newer engines last longer and give max performance for longer intervals, but they are throw away motors. That’s the general consensus, but let’s answer your questions individually:

• Can you enlighten me about what people do these days when their engines are wearing? Back to the term “throw away motor”, as people normally get another motor from LKQ (or similar computer-intensive junkyard) and swap them out. Rebuilding a modern motor isn’t a very bright idea, unless the car is super valuable with the original block or you want extra power from a big-bore re-sleeve, like this Lingenfelter job for LSX-FTW engines.
• Are valve jobs common? Heck, I can’t find anything to prove that valve jobs even happen (in significant quantities) these days, much less being a common practice. Again, throw away motors mean you can find a better one elsewhere. But more importantly, engines don’t wear out like they used to. Reduced performance from worn out valve train isn’t a big deal anymore.
• Are some brands more repairable than others? If you live in the US, the most repairable brands will be from Detroit. Parts are plentiful, cheaper and more local machine shops will do the work without needing further research. Sadly (or not?), the art of repairing an engine is more of a niche service these days. At least for mainstream vehicles, like those once powered by GM’s 2.5L Iron Duke. I suspect Japanese brands are a close second, everything else shall be challenging and/or cost prohibitive. Not that people aren’t tweaking AMG and BMW motors regularly in the USA…but the best motor to get your (pushrod-loving) hands dirty these days is a Chevy (Truck) LS motor with an iron block.
• What lifespans do people expect from modern engines? With the use of synthetic oil, regular fluid changes and tune ups, I think most folks expect over 150,000 miles from their engines. And that’s being modest: 200+k is likely. Provided most 1-owner cars aren’t traded in well before this time, of course. Our society of consumption makes this personal expectation question most difficult to answer!

Some engines have proven otherwise (sludgy VWs and Toyotas, piston-slapping Chevys, head gasket eating Subies, etc) but one fact remains: advances in 1) metallurgy 2) technology 3) production means that the old ways of your pushrod motors (and my Windsor V8s, FWIW) are a thing of the past.

And we are far better off this way.

Send your queries to sajeev@thetruthaboutcars.com. Spare no details and ask for a speedy resolution if you’re in a hurry…but be realistic, and use your make/model specific forums instead of TTAC for more timely advice.